The present invention relates to a system for controlling the amount of intake air in an automotive engine, and more particularly to a system for controlling the intake air at rapid closing of a throttle valve of the engine.
When the throttle valve closes rapidly after the driver releases the accelerator pedal, air-fuel mixture can be momentarily excessively enriched. This causes an increase of the hydrocarbon and carbon monoxide content in the exhaust gases. To prevent increase of the pollutants, the motor vehicle is equipped with a dashpot or a control valve in a bypass around the throttle valve.
The dashpot is adapted to prevent the throttle valve from rapidly closing. The control valve is arranged so as to slowly close to control the amount of intake air so as to prevent excessive enrichment of the air-fuel mixture. On the other hand, pollution of the exhaust gases by rapid closing of the throttle valve is aggravated during the warming up operation of the engine. However, if the intake air control systems are designed so as to prevent the enrichment in accordance with conditions during warming up, the driveability of the vehicle deteriorates at normal operating temperature. Accordingly, it is difficult to provide an intake air control system which may resolve this inconsistent problem.